The HAM Guide To JSB KnockOut Slugs

JSB KnockOut slugs have a great reputation in the market for downrange accuracy and hitting power. Today we’ll look at the different types and calibers that are available for this popular airgun ammo.

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JSB KnockOut Slugs – Summary​

KnockOut slugs are available in four calibers. Starting with .177, there’s .22, .25 and .30 caliber products, as this table shows.

.177	.22	.25	.30
Original (Mk. 1)	Yes	Yes	Yes	Yes
Mk. 2	Yes	Yes	Yes
Mk. 3	Yes

But the chart also shows a range of different configurations. There’s the original models, then Mk. 2 and Mk. 3 models.

We’ll take a look at the differences to help you make the best choice for your needs.

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JSB KnockOut Slugs – Marks​

First a word about the product designations…

Like several European manufacturers, JSB uses the “Mark” designation to differentiate similar products. “Mark” is often abbreviated as “Mk.”. It’s not pronounced “M, K” as separate letters.

Probably the most common use of the “Mark” concept was by the British army. For example, the standard British Second World War Lee Enfield service rifle was produced as the “Number 4, Mark 1” and “Number 4, Mark 2″ versions. (Abbreviated as “No. 4 Mk. 1” and “No. 4 Mk. 2”).

Below. An example of British military usage can be seen on the breech of this Lee Enfield.

But there’s a subtle difference between JSB’s usage of the “Mark” designation and the British army prototype. In British military usage, the Mk. 2 version replaced the Mk. 1 in production. In the case of JSB, the Marks 1, 2 and 3 are all in production at the same time!

JSB KnockOut Slugs – Mark 1

These – the original pattern JSB KnockOut Slugs are homogeneous slugs shaped to give high ballistic coefficient and a flatter trajectory than standard pellets. The hollowpoint cavity is relatively small to gives reliable expansion on contact while minimizing velocity loss.

Below. Mushrooming? Yip!

JSB KnockOut Slugs – Mark 2

These JSB KnockOut Slugs incorporate an updated flared skirt design which helps to improve stability in flight and leads to efficient power and works with the overall design to deliver greater accuracy.

JSB KnockOut Slugs – Mark 3

The goal of this version is even greater in-target expansion. To that end, these JSB KnockOut Slugs have a larger hollow point cavity. So far, they are available in .177 caliber only.

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JSB KnockOut Slugs – Calibers​

Now let’s look in more detail at the different configurations of KnockOut slugs that are available in each caliber.

.177 Caliber

Here we have two head diameters, a choice of two weights and all three Marks.

Mk. 1	Mk. 1	Mk. 2	Mk. 3
Diameter (mm)	4.51	4.52	4.51	4.51
Weight (Grains)	10.03	13.43	10.03	10.03
Ballistic Coefficient	0.047	0.066	0.047	0.047

Below. Seen in the same order…

.22 Caliber

JSB includes the most choices in this most popular caliber for PCP air rifle shooters. There’s three head diameters and a choice of three different weights. But no Mk. 3 version with bigger hollowpoint cavity.

Mk. 1	Mk. 1	Mk. 1	Mk. 1	Mk. 1	Mk. 2
Diameter (Inches)	0.216	0.216	0.217	0.217	0.218	0.216
Weight (Grains)	20.83	25.39	25.39	28.55	25.39	25.39
Ballistic Coefficient	0.088	0.084	0.084	0.087	0.084	0.086

Below. .217 caliber, 28.55 Grain slugs.

.25 Caliber

In this caliber, there’s a choice of two options. Both have the same weight – 33.49 Grains. However there’s 0.250 and 0.251 Inch diameters.

.30 Caliber

Just one choice here. 50.15 Grains weight and 0.30 Inches diameter.

BUY FROM PYRAMYD
JSB KnockOut Slugs .216 Cal, 20.83gr, Hollowpoint, 200ct 0.22

The post The HAM Guide To JSB KnockOut Slugs appeared first on Hard Air Magazine.

 

[Pumacarl]

If you own a .177 the Mk3 has no equal in killing Starlings! The sleeper KO is the .22 .216 20.83gr, just outstanding.

 

[Doc Holiday]

I know nothing about slugs except hearing you need a certain twist rate and an airgun of a certain power level (both for accuracy). So how powerful does the gun need to be? Is it pcp only? Or maybe some break barrels? Maybe the two most powerful pumpers (dragonfly & 362)?

 

[Solo1]

177 is generally in my opinion most capable of shooting slugs if it can get enough velocity. Slugs in everything else is a bit more difficult and something you need to work out for every different gun. My revere 22 for example shoots 17 gr 2165 nsa very well but thats the only 1.

 

[Pumacarl]

I have a Hatsan Vectis setup to average 21fpe that has a 100 percent kill ratio on Starlings out to 75y. I handpump that gun, no regulator, always good first shot.

 

[Bladefin]

It's confidential that this came out this week. I recently bought 4 tins of .25 KO mk2's with a freebie from Pyramid.
These shot the best overall for me, they grouped ok, just not great. But there would be odd flyers or ones that would drop. So I decided to weigh sort them last weekend. I was shocked at the variance! Zan's were vary consistent on their weight, these were like a bell curve. I found that odd with such a tightly listed grain of 33.49 they would be close to that. I had some as light as 32.82 and as heavy as 34.28, with the vast majority 33.56 to 33.94.

 

[hameditor]

It's confidential that this came out this week. I recently bought 4 tins of .25 KO mk2's with a freebie from Pyramid.
These shot the best overall for me, they grouped ok, just not great. But there would be odd flyers or ones that would drop. So I decided to weigh sort them. I was shock at the variance! Zan's were vary consistent on their weight, these were like a bell curve. I found that odd with such a tightly list grain of 33.49 they would be close to that. I had some as light as 32.82 and as heavy as 34.28, with the vast majority 33.56 to 33.94.

View attachment 22148

Every type of pellets and slugs that HAM has ever reviewed shows a bell curve distribution of weights. So I'm not surprised at all. Airgun Pellet Test Reviews Archives - Hard Air Magazine

JSB specifies a factory limit for weight consistency of up to 2.5% difference between individual pellets. You can see that at Info - JSB Match Diabolo - pellets, ammunition

Based on our testing, I'd say JSB's claim is a pretty tight tolerance aim for tiny items made in huge numbers for a remarkably low price.

Of course, weight is not the only variable. In HAM test reviews we measure length and (head) diameter too. There's always some sort of bell curve for all of these measurements. Head diameter is generally the most consistent, length the most variable.

Then there's the stuff we would love to measure but don't have the technology to do so. For example, concentricity and center of gravity. All of these factors will make a difference in downrange accuracy. The question is how much?

You can see more in the reviews here Airgun Pellet Test Reviews Archives - Hard Air Magazine

BTW. We're weighing with a laboratory-grade Sartorius milligram balance that retails at about $1,500.00 today, so we're pretty confident in our weight measurements.

 

[Pumacarl]

It's confidential that this came out this week. I recently bought 4 tins of .25 KO mk2's with a freebie from Pyramid.
These shot the best overall for me, they grouped ok, just not great. But there would be odd flyers or ones that would drop. So I decided to weigh sort them last weekend. I was shocked at the variance! Zan's were vary consistent on their weight, these were like a bell curve. I found that odd with such a tightly listed grain of 33.49 they would be close to that. I had some as light as 32.82 and as heavy as 34.28, with the vast majority 33.56 to 33.94.

View attachment 22148

I've noticed most brands have shining stars and shirttail riders, the two I mentioned shoot awesome. I would never go through a sorting process, I'd keep looking for something that my gun just likes out of the tin. I like working on the guns, not store bought ammo. If I was a little younger though, I'd make my own and control the whole process.

 

[Billm]

You can’t always use the manufacturer’s specified weight as a precise. They know most cheap scales aren’t that accurate. In several cases they sell the same pellets under different weights even though they are identical pellets. I don’t bother sorting AEA as the small differences in weight don’t seem to make any real world difference. That may just be my experience. My scale reads to .01 gr. I say that with a smile and a look of doubt.